Author: mjg
Date: Sun Dec 13 21:29:39 2020
New Revision: 368615
URL: https://svnweb.freebsd.org/changeset/base/368615
Log:
cache: fix ups bad predicts
- last level fallback normally sees CREATE; the code should be optimized to
not
get there for said case
- fast path commonly fails with ENOENT
Modified:
head/sys/kern/vfs_cache.c
Modified: head/sys/kern/vfs_cache.c
==============================================================================
--- head/sys/kern/vfs_cache.c Sun Dec 13 21:28:15 2020 (r368614)
+++ head/sys/kern/vfs_cache.c Sun Dec 13 21:29:39 2020 (r368615)
@@ -1824,7 +1824,10 @@ retry:
}
return (-1);
negative_success:
- if (__predict_false(cnp->cn_nameiop == CREATE)) {
+ /*
+ * We don't get here with regular lookup apart from corner cases.
+ */
+ if (__predict_true(cnp->cn_nameiop == CREATE)) {
if (cnp->cn_flags & ISLASTCN) {
counter_u64_add(numnegzaps, 1);
error = cache_zap_locked_bucket(ncp, cnp, hash, blp);
@@ -1927,7 +1930,7 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, st
}
return (-1);
negative_success:
- if (__predict_false(cnp->cn_nameiop == CREATE)) {
+ if (cnp->cn_nameiop == CREATE) {
if (cnp->cn_flags & ISLASTCN) {
vfs_smr_exit();
goto out_fallback;
@@ -4589,7 +4592,10 @@ out:
case CACHE_FPL_STATUS_HANDLED:
MPASS(error != CACHE_FPL_FAILED);
cache_fpl_smr_assert_not_entered(fpl);
- if (__predict_false(error != 0)) {
+ /*
+ * A common error is ENOENT.
+ */
+ if (error != 0) {
ndp->ni_dvp = NULL;
ndp->ni_vp = NULL;
cache_fpl_cleanup_cnp(cnp);
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